Hourglass magnet

ABSTRACT

The invention is intended for incorporation into an enclosure confining fluid about an electromagnet of the type having a core, at least one coil disposed about the core and a current source coupled to the coil to establish a magnetic field. According to the invention, at least a portion of the peripheral wall of the enclosure surrounding the core axis resides in non-parallel relationship with the axis of the core. As a result, a part of the peripheral wall portion is in closer proximity to the wire coil than the remainder of the wall portion. As a result, the heat readily conducts through the wall portion and is dissipated efficiently. The surface exposed to the atmosphere with the above construction has a greater area than would a planar wall parallel to the core axis so that heat dissipation is enhanced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to electromagnets with enclosures confining acooling fluid and, more particularly, to an improved enclosure for thefluid which enhances heat dissipation.

2. Background Art

It is known to provide an enclosure about an electromagnet to confinefluid about coils associated with the magnet to cool and thereby extendthe useful life of the magnet. It is known, for example, to provide asquare enclosure about an electromagnet with a cylindrical core. Becausethe core may have a relatively small axial dimension, the surface areaof the surrounding side walls exposed to the atmosphere may not besufficient to effectively dissipate the generated heat.

SUMMARY OF THE INVENTION

The present invention is specifically directed to overcoming the aboveproblem in a novel and simple manner.

The invention is intended for incorporation into an enclosure confiningfluid about an electromagnet of the type having a core, at least onecoil disposed about the core and a current source coupled to the coil toestablish a magnetic field. According to the invention, at least aportion of the peripheral wall of the enclosure surrounding the coreaxis resides in non-parallel relationship with the axis of the core. Apart of the peripheral wall portion is therefore in closer proximity tothe coil than the remainder of the wall portion, causing the heat to beabsorbed readily by the wall portion through conduction. The surfaceexposed to the atmosphere with the above construction has an exposedradiating surface area greater than a wall that is planar and parallelto the core axis so that heat dissipates to the surrounding atmospherein a quick and efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electromagnet with an enclosureaccording to the present invention; and

FIG. 2 is a sectional view of the electromagnet and enclosure along line2--2 of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

The invention contemplates use with a conventional electromagnet of thetype depicted in FIGS. 1 and 2. A cylindrically shaped, solid steel core10 is surrounded by preferably from four to seven anodized, aluminum,annular strip coils 12. The coils are stacked to be axially coincident,connected in continuous manner and coupled to a current supply 14. Anoutlet box 16 is provided externally of an enclosure at 18 envelopingthe core and coils. A flat steel headplate 20 seats facially against theupper surface of the core and overlaps the the coil diameter. The plate20 spreads out the magnetic flux to prevent saturation. Immediatelyabove the head plate and in facial engagement with the upper, planarsurface 22 of the head plate is a steel top plate 25 which, inconjunction with a bottom plate 24 defines a unitary assembly bounding achamber 26 within which cooling fluid is confined about the core andcoils. Preferably, the bottom plate is non-magnetic stainless steel andwelded directly to the bottom of the core. A steel impact plate 27 iscentered on and welded to the bottom plate 24. The impact plate 27protects the bottom plate 24 and creates an evenly distributed magneticfield and a marked increase in flux density over a like structurewithout the impact plate 27.

The invention resides in the peripheral side wall structure at 28surrounding the axis of the core which, in conjunction with the top andbottom plates, defines the fluid tight enclosure 18. The top and bottomplates are substantially square so that the side wall structure 28 isdefined by first and second pairs of facing side walls 30, 32 and 34,36. In one form of the invention, each of the walls 30, 32 of the oneside wall pair are planar and extend parallel to the axis of the core 10and are welded conventionally to the top and bottom plates to establisha leakproof seal.

The walls 34, 36 may be identical to each other in construction. Theside wall 34 will be described in detail to exemplify the constructionof walls 34, 36. Each of the walls 34, 36 is formed from a single steelblank. Each wall is formed by bending a substantially rectangular platelengthwise about its mid portion to, for instance, a right angle. Thewall 34 is dimensioned so that the upper wall portion 38 extendsangularly inwardly from the edge 40 of the top plate 25 towards the coreto an apex 42 from where the bottom portion 44 is return bent so thatthe free edge 46 matches with the upper surface 48 of the bottom plate24. The wall edges 40, 46 are welded respectively to the top and bottomplates. The dimensions of the top and bottom plates and the spacingtherebetween is chosen so that the apex 42 of the wall 34 is spacedslightly from the outer peripheral surface 50 of the coils 12. Thestructure in vertical cross-section appears as an hourglassconfiguration. With the enclosure completed, a cooling fluid isintroduced to fill the chamber 26.

It can be seen that, because of the close proximity of the apex 42 ofthe wall 34 to the coil, that the heat from the coil readily conductsthrough the cooling medium through the apex 42 and diagonally to wallportions 38, 44. The wall portions 38, 44 define flat surfaces 52, 54respectively, which are exposed to the atmosphere. The combined area ofthe surfaces 52, 54, by reason of the bent wall design, is greater thanthe area would be if the wall was planar and extended parallel to theaxis of the core between the top and bottom plates. Not only is theradiating surface area of the wall 34 increased, but triangular heatradiating surfaces 56, 58 of each wall 30, 32, formed at the overlap bywalls 30, 32 of walls 34, 36, are exposed to the atmosphere to furtherenhance heat dissipation, whereas in a square, conventional constructionthe surfaces 56, 58 would be immersed in the cooling fluid. With theenclosure according to the invention, heat continually dissipates to thesurrounding atmosphere in a quick and efficient manner.

The foregoing description was made for purposes of demonstrating thestructure and operation of the present invention, with no unnecessarylimitations to be understood therefrom.

I claim:
 1. An improved enclosure for confining a cooling fluid about anelectromagnet of the type having a core with a core axis, at least onecoil disposed about the core and a current source coupled to the coil toestablish a magnetic field, the improvement comprising:at least aportion of a peripheral wall of the enclosure surrounding the core axishaving a configuration that presents a substantially increased surfacearea to the cooling fluid and to the atmosphere than a comparablestraight wall between a top and a bottom wall of the electromagnet, andsaid cooling fluid bathes the coil and the inside surface of theperipheral wall, whereby at least a part of the peripheral wall portionis in closer proximity to the coil than the remainder of the wallportion to enhance absorption and dissipation of heat therefrom.
 2. Theimproved enclosure according to claim 1 wherein said peripheral wallportion in axial cross section comprises substantially a V-shape withthe V opening radially away from the axis of the core.
 3. The improvedenclosure according to claim 1 wherein said enclosure comprises top andbottom plates at the axial ends of the core and first and second pairsof facing walls sealing between the plates, at least one said wall inone of the wall pairs directed from the top plate inwardly toward thecore at least partially between the top and bottom plates.
 4. Theimproved enclosure according to claim 1 wherein said enclosure comprisestop and bottom plates at the axial ends of the core and first and secondpairs of walls sealing between the plates, at least one said wall on oneof the wall pairs directed from the top plate radially inwardly towardthe core to an apex and returned radially outwardly from the core fromthe apex to the bottom plate.
 5. An improved enclosure for confining acooling fluid about an electromagnet of the type having a core with acore axis at least one coil disposed about the core and a current sourcecoupled to the winding to establish a magnetic field, the improvementcomprising:said enclosure having substantially parallel, spaced top andbottom plates at the axial ends of the core and first and second pairsof sealing walls between the top and bottom plates, at least one saidwall in one of the wall pairs having a heat dissipating surface exposedto the atmosphere with a non-planar configuration between the top andbottom plates; said non-planar configuration presenting an increasedheat receiving surface to the cooling fluid and an increased heatdissipating surface to the atmosphere.
 6. An improved enclosure forconfining a cooling fluid about an electromagnet of the type having acylindrical core, at least one coil disposed about the core and acurrent source coupled to the winding to establish a magnetic field, theimprovement comprising:top and bottom plates at the axial ends of thecylindrical core; first and second facing wall pairs cooperativelysealing between the top and bottom plates; the walls in one said wallpair each having at least a portion with a V-shape in axialcross-section, said V on each wall in the one wall pair opening awayfrom the V on the other wall in the one wall pair, said V-shaped wallspresenting an increased heat receiving surface to the cooling fluid andan increased heat dissipating surface to the atmosphere.
 7. The improvedenclosure according to claim 6 wherein a substantially flat head plateresides between the core and the top plate to spread out magnetic fluxand prevent saturation.
 8. The improved enclosure according to claim 6wherein another of the walls overlaps the V and has a surface within theV exposed to the atmosphere to further enhance heat dissipation.